Buoyancy control device



May 28, 1957 R. D. ATCHLEY BUOYANCY CONTROL DEVICE Filed May 3, 1944 2. Sheets-Sheet l INVENTOR RA-YMND D. ATcH LEY BY HTIU Y May 28, 1957 Filed May 3,- 1944 R. D. ATCHLEY BUOYANCY CONTROL DEVICE 2 Sheets-Sheet 2 INVENToR l RAYMOND u ATCHLEY 2,793,589 BUGYANCY CGNTRL DEVKCE Application May 3, 1944, Serial No. 533,895

S Ciainis. (Cl. IGZ- 14) This invention relates to a device for controlling the buoyancy of an object when it is submerged in a medium such as water.

It often becomes necessary to suspend an object at a particular level in a medium and to maintain it at this level under all conditions for a considerable period of time. The problem is made diicult because currents may cause the object to vary in depth or suspend itself at one or more undesirable levels. Additionally, since the complete unit (including the buoyancy control and the object to be suspended) is entirely surrounded by a medium, the buoyancy control mechanism must be arranged to be unafected by corrosion, rust or chemical reaction with such medium. Another diiculty which must be overcome is the rising or sinking of the device, if, for any reason, the total weight or total displacement is altered or changed by operation of the unit, effects of high pressure, damage, etc.

It is therefore clear that one Yof the objects of the invention is a buoyancy control which will maintain an object at a predetermined level in a medium. It is also an object of the invention to provide such a device which is exceedingly simple, with a minimum number of moving parts so that accurate operation will always be obtained. The present invention also provides means for quickly setting the mechanism to cause it to suspend itself at any desired level.

In many instances it is also necessary to provide a mechanism which will suspend itself at a predetermined level and maintain that level regardless of a loss or gain in weight or displacement ot any part of the complete unit. In the past, most buoyancy controls have been constructed to operate in a manner that for any given setting of the mechanism, the level at which zero buoyancy was eiected depended on the weight and/ or displacement of the device. In other words, the eiective volume of the buoyancy chamber was determined by the pressure (i. e., the level in the medium) at the point at which the device was positioned. Thus, if the device gained weight and began to sink, the increased pressure caused (by any one of the several means) the volume of the buoyancy chamber to be increased and the device to be brought to a point of lesser pressure and depth. But, since an added weight would necessitate a larger buoyancy chamber (to maintain zero buoyancy) it was obtained only when the pressure was greater than that needed before the additional weight had been added. This additional pressure naturally could be obtained only at a greater depth and the zero-buoyancy level was thus at a greater depth in the medium.

The present invention is designed to overcome this diiculty and always maintains zero buoyancy at the same level in the medium, regardless of changes in weight or displacement of the entire unit as long as these changes do not exceed the difference between the weicht of the buoyancy chamber full of water and full of gas. This is accomplished by means of a valve which is controlled 2,793,589 Patented May 28, 1957 by the pressure in the surrounding medium. This Valve is designed to regulated the escapeof gas (supplied from a convenient source) from the buoyancy chamber. When the ydesired level is reached, the external pressure is such as to hold the valve in a position which allows gas to escape the buoyancy chamber atthe same rate at which it is generated. lf the pressure decreases below that at this zero-buoyancy level, the valve opens wider and allows gas to escape at a rate faster than it is being generated, thus allowing water to displace the gas. This decreases its buoyancy Iand .the `device sinks again to the Zerobuoyancy level. Conversely, if the external pressure increases, the valve is moved to limit the escape of the gas to a rate below the generated rate. This causes displacement of water by gas, increases the buoyancy, and the device necessarily rises. It is thus seen that the invention consists in the provisionof a relatively continuous flow of gas and a valve, automatically controlled by the external pressure, which, at the zero-buoyancy level, allows the gas to escape at the same rate at which it is being generated. Changes in the actual total weight which do not exceed the difference in weight between the buoyancy chamber full of water Vand full of `gas have no effect on the operation of the buoyancy control as the valve is sensitive only to pressure.v

In some'cases it is desirable to make the device expendible and to sink to the bottom when through functioning. The present invention is made expendible by the fact that when the gas source is exhausted, enough of the trapped gas escapes to give it la negative buoyancy which causes it to sink tothe bottom,

In the drawings:

Figure 1 is la schematic drawing showing the elements of the invention.

Figure 2 isa side view, partially in section, of one form of the invention. K

' Figure 3 is a top view of the forni of the invention shown in Fig. 2, Y

The inventionl is schematically illustrated in. Fig. l and this drawing will be used to illustrate the principal elements and the operation of the device. It consists primarily of a hollow buoyancy chamber 1 with its open end positioned downward. Supported on a ilange 2, internally of the chamber, is a cylinder 3. A waterand air-tight piston 4 is mounted for movement within cylinder 3, and its connecting rod 5 extends through a bearing` in the closed upper end of the chamber. The cylinder 3 and water-tight and air-tight piston 4 may be in the form of an air-filled metallic bellows or Sylphon unit not here illustrated in Figure 1, but shown in Figure 2. The metallic bellows embodiment is substantially friction-free and sensitive to small changes in pressure diilerentials. On the other end of the rod, externally of the chamber, is a circular poppet valve 6, which is designed to operate against a circular raised valve seat 7 formed on the chamber 1.

In the lower part of the chamber 1 is a gas supply 8 which is arranged to supply gas within the chamber at a relatively constant and continuous rate. A series of holes 2a is formed in flange 2 and in the top of the chamber within the circumference of the valve seat to allow the gas to pass through and out of the buoyancy chamber. The block W schematically represents the total weight of the buoyancy control and any attached unit.

When the device is submerged, the surrounding or external pressure P1 creates a force on the upper side of piston 4. As the device goes deeper in the medium, this pressure increases, forcing the piston into cylinder 3; conversely, when the pressure'decreases, the piston moves upwardly and out of the cylinder. At all times, gas is supplied from source 8 and bubbles up through the holes in flange 2 and, when valve 6 is open, out through the holes in the top of the chamber. It is seen that there is some particular external pressure which will cause the valve 6 to be open to allow the gas to escape from the chamber at the same rate at which it is generated. If this pressure is decreased, valve 6 allows the gas to escape at a rate faster than it is being generated, water displaces some of the trapped gas, decreasing the buoyancy until the device sinks to the proper level. If, on the other hand, the device is caused to sink below this proper level, the increase in pressure causes the valve to move to a more closed position to reduce the escape of gas.

In this condition, gas displaces some of the water, in-

creasing the buoyancy, and the device rises. In this connection, it should be noted that in practice, connecting rod 5 may be made extensible by means of a spring so that if valve 6 is completely closed, a further increase in pressure will allow piston 4 to move further into cylinder 3, without altering the position ofthe valve. This maintains an equality between the values of pressures P1 and P0 and avoids possible leakage between the piston and the walls of the cylinder or collapse of the metallic fr ing the position of valve 6 on rod 5, to obtain the proper opening of the valve to insure this equality of escape and generation rates at any desired pressure. Since pressure varys directly with depth in a liquid medium, the device nay obviously be made to come to rest at any desired evel.

It is also clear from the above that the weightiW of 4 the device (and any attached mechanism) is of no consequence in the operation of the invention as long as it does not exceed the diiference between the weight of the buoyancy chamber full of water and'full of gas. Its operation is dependent upon the value of the reference pressure PR. If the surrounding pressure P1 increases to a value greater than the reference pressure, the gasescape rate will be less than the generation rate, some of the water in the chamber will be displaced by the gas, and theV increased buoyancy will cause the device to rise. Conversely, if the external pressure decreases such that the valve opening will be large enough to allow an escape rate greater than the generation rate, the water will displace some of the gas and the decreased buoyancy will cause the device to sink.

The device illustrated in Fig. 2 is one which has proven very satisfactory for a large range of working conditions and will be described in detail. Parenthetically, it should be stated that it is'not intended to limit the invention to the structure shown in these gures, but that it simply illustrates one manner of construction which may be altered in any way consistent with the broader invention described herein. In Fig. 2, the buoyancy chamber 11 (shown in section) is seen to be formed from a hollow tube whose upper edges are rolled inwardly, and a bracket 12 (shown partially in section) whose upper edges are crimped over the end of chamber 11, as at 13, to form a valve scat, is positioned centrally of the upper end of the chamber. This bracket is openV at one or more (points as at 14 to assure uniform distribution of pressure. The bracket is drilled and provided with internal threads 15 at its lower end to recciveand position a convention metallic bellows 16 which has its own Yspring tension, so that its length may be controlled directly by pressure. The metallic bellows is provided with a threaded extension 17 at each of its ends. Y The lower end of these extensions secures the metallic bellows on the bracket and extends through it to receive a lock nut 18 on its outer end. The upper extension threads into the lower end of a rod 19 (shown partially in section), countersunk at each of its ends. Rod 19 is positioned by means of a surrounding circular plate 20 which rests on an internal flange 21 at the upper end of bracket 14. 'A series of holes is formed in plate 20, positioned around rod 19.

The louter end Aofrod n19 mounts a poppet valve 22 which-is positioned against a liange on the rod by crimping the outer end 23 of the rod over and against it, as shown in Fig. 2, As Call be seen, the valve is closed when it is moved against seat 13. Y

A suitable container 2S is mounted by means of clamps 26 in the lower end of chamber 11. The container illustrated in Fig. 2 is one provided with an open upper end and contains a chemical or chemicals, such as a mixture of one part of lithium hydrideV with fteen parts of sodium acetate which, when exposed to water, give off or generate gas. However, it is clear that any other convenient source of gas, such as compressed gas cartridges, liquid gas containers, etc. may be used. It is not necessary that the gas container be mounted within chamber 11, so long as the ejection nozzle or opening is positioned to allow the gas to enter said chamber. lt is also convenient for smooth operation to provide a gas source which will emit gas at a relatively constant and continuous rate.

The operation of the device illustrated in Figs. 2 and 3 is very similar to that describedrwith reference to the schematic system of Fig. -1. As ythe pressure P1 increases or decreases, Vthe contraction or expansion of the metallic bellows causes valve 22 to close or open, respectively.' When the pressure P1 is such that the valve 22 is held open just sufcient to allow the escape of gas at` the same rate at-which it is being generated, there will be no change in the amount of displaced water in chamber 11 and the device will remain ysuspended at that level. above.'l IfY the device is forced toV a greater depth (i. e., a higher pressure), the'valve partially closes untilvthe gas escapes at a rate less than that at which it is generated. This causes some of the water in chamber 11 to be displaced by the gas, and the device becomes positively buoyant and rises. If for some reason, i't'rises above the zero-buoyancy level, where pressure P1 becomes less than the reference pressure PR, some of the gas in the chamber is displaced by water and the device sinks. Thus, as has been stated, only when the external pressure P1 is such that metallic bellows maintains the valve open to a degree allowing the escape of gas at the same rate as it is generated, will theV device remain at the desired level; i

This pressure is designated PR, as deiined Since the zero-buoyancy level at which the device suspends itself is determined by the amount by which valve 22 is open when the gas escape and generation rates are equal, it is possible to predetermine the zero-buoyancy level by screwing the metallic bellows in or out of bracket 14, and locking it in position by means of nut'lS. If desirable, the extension 17 on the lower end of the metallic bellows may be calibrated, by means of which the device may be made to suspend-itself at any desired level.

A buoyancy control of the Vtype just described in which the buoyancy chamber 11'measured'approxirnately 3 inches in diameter and 31/2 inches long (with a total weight of about 6 ounces) has been found to operate very satisfactorily. This particular model successfully supported a unit at any desired depth and automatically compensated for a buoyancy correctionV (gain or loss of weight or displacement) of about 1A pound. The amount of buoyancy correction possible is, of course, limited by the-sizeof the buoyancy chamber, which may be arranged to have any desirable volume. v

Since the amount of gas available for use in any type of device is limited, the entire unit automatically sinks to the bottom of the medium when gas is no longer available. When gas is no longer produced, most, if not all, of the gas entrapped in the buoyancy chamber escapes before the unit sinks to a depth where the pressure is sucient to completely close the valve. Since there is no longer any provision for producing positive buoyancy, the device sinks to the bottom.

Having described my invention, l claim:

1. A buoyancy control device comprising a housing with a downward facing mouth opening small top opening, an upward facing cup member, means fastening said cup member within said mouth opening, a gas generating chemical carried within said cup member, valve means comprising a valve mounted adjacent said top opening, and valve operating means in said housing for operating said valve, whereby said valve selectively opens or closes said top opening for controlling the release of gas from said housing.

2. A buoyancy control device comprising a housing with a downward facino mouth opening and a small top opening, an upward facing cup member, means fastening said cup member within said mouth opening, gas generating means carried within said cup member, a mounting bracket in said housing having upper edges secured to the edge of the said top opening to form a valve seat, a valve head adapted to coact with said seat, means mounting said valve head on said bracket, and valve actuating means for controlling operation of said valve head.

3. A buoyancy control device as in claim 2 wherein said valve actuating means comprises a metallic bellows, means attaching one end of said bellows to said head and its other end to said mounting bracket.

4. A buoyancy control device as in claim 3 wherein said bellows having a threaded extension piece integral 6 therewith is threadedly attached to said bracket whereby spring tension of said bellows may be varied.

5. A buoyancy control device suspendable in a surrounding medium, comprising a housing with a downward facing mouth opening and a small top opening, an upward facing cup member, screws fastening said cup member within said mouth opening, a gas generating chemical carried within said cup member, said chemical adapted to generate gas upon contact with the surrounding medium, a valve supporting bracket within said casing, means securing the upper end of said bracket to the walls of said top opening provided in said housing thereby forming a valve seat, a valve, means positioning said valve adjacent said valve seat for coaction therewith, said valve positioning means comprising a rod and a metallic bellows, said rod secured at one end to said valve and at the other end to the upper end of said metallic bellows, and means mounting lower end of said metallic bellows on the lower end of said bracket, whereby said bellows responds to the pressure of surrounding medium for controlling the flow of gas through said top opening at a rate substantially equal to the rate of its generation when the pressure in the surrounding medium reaches a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS 1,038,139 Howard Sept. 10, 1912 1,440,596 Hammond Jan. 2, 1923 1,733,525 Clifford Oct. 29, 1929 2,103,614 Day Dec. 28, 1937 FOREIGN PATENTS v 24,821 Great Britain 1914 38,603 Sweden Mar. 24, 1915 

